A cave automatic virtual environment (CAVE) projection system is a large virtual reality (VR) system (such as VR-Platform CAVE), with a high degree of immersion and interactivity. The CAVE projection system can fuse vision, touch, sound and so on, and can track head movement along 6 degrees of freedom. The principle of a CAVE immersive virtual reality display system is relatively complex. It is based on computer graphics, and perfectly fuses the high-resolution three-dimensional projection display technology, multi-channel visual synchronization technology, three-dimensional computer graphics technology, audio technology, sensor technology and so on together to produce a completely immersive virtual environment surrounded by a three-dimensional projection screen and used by multiple people. At present, real-time high-resolution multi-window content rendering of a complex scene is mainly applied to the CAVE system. The CAVE projection system is a large VR system with the high degree of immersion and interactivity. The CAVE projection system is a highly immersive virtual demonstration environment composed of three or more (including three) hard rear-projection walls. An observer is surrounded by the virtual reality system with a plurality of images, and a plurality of projection surfaces form a virtual space. The common CAVE system projection space is a standard cubic structure, and the four independent projection channels finally form a space continuous projection image.
Currently, the advantage of using the conventional projector with multiple optical machines to achieve the projection in a surrounding manner or in a large range is to meet the requirement for an engineering projector on the projection distance in huge physical space. The conventional projector technically achieves large frame surrounding projection under the household scale space (small and medium space). However, the disadvantage of the conventional projector is that the distance between the projection surface and the optical machine is too short when the projector is used in a smaller micro space; and the conventional projector cannot meet the requirement that the size of the projection surface does not need to use a special optical machine with short focal length, and the conventional projector cannot use an optical machine with common focal length to achieve the frame covering the small space and micro space.